Reactive Molecular Simulation on Water Confined in the Nanopores of the Calcium Silicate Hydrate Gel: Structure, Reactivity, and Mechanical Properties

Abstract

Calcium silicate hydrate (C-S-H) is a mesoporous amorphous material with water confined in the gel pores, which provides the medium for investigating the structure, dynamics, and mechanical properties of the ultraconfined interlayer water molecules. In this study, C-S-H gels with different compositions expressed in terms of the Ca/Si ratio are characterized in the light of molecular dynamics. It is found that with increasing Ca/Si ratio, the molecular structure of the silicate skeleton progressively transforms from an ordered to an amorphous structure. The calcium silicate skeleton, representative of the substrate, significantly influences the adsorption capability, reactivity, H-bond network, and mobility of the interlayer water molecules. The structures were tested for mechanical properties by simulated uniaxial tension, and the mechanical tests associated with structural analysis reveal that the stiffness and cohesive force of C-S-H gel is weakened by both breakage of silicate chains and penetration of water molecules. In addition, the reactive force field is coupled with both the mechanical response and chemical response during the large tensile deformation process. On the one hand, the silicate chains, acting in a skeletal role in the layered structure, depolymerize to enhance the loading resistance. On the other hand, water molecules, attacking the Si-O and Ca-O bonds, dissociate into hydroxyls, which are detrimental to the cohesive force development.

Department(s)

Civil, Architectural and Environmental Engineering

Keywords and Phrases

Amorphous Materials; Calcium; Chains; Hydrates; Hydration; Mechanical Properties; Molecular Dynamics; Molecular Structure; Molecules; Musculoskeletal System; Silicate Minerals; Silicates; Stiffness; Adsorption Capability; Amorphous Structures; Calcium Silicate Hydrate; Calcium Silicate Hydrate Gel; Mechanical Response; Molecular Simulations; Reactive Force Field; Tensile Deformation; Calcium Silicate

International Standard Serial Number (ISSN)

1932-7447

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2015 American Chemical Society (ACS), All rights reserved.

Publication Date

01 Jan 2015

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